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                        数据结构与算法（Python）
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                            <b>1.</b>
                        
                        引入概念
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                            <b>1.2.</b>
                        
                        算法的提出
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                            <b>1.3.</b>
                        
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                            <b>1.4.</b>
                        
                        算法效率衡量
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                            <b>1.5.</b>
                        
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                            <b>1.7.</b>
                        
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                            <b>1.8.</b>
                        
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                            <b>2.</b>
                        
                        顺序表
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                            <b>2.1.</b>
                        
                        顺序表的形式
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                            <b>2.2.</b>
                        
                        顺序表的结构与实现
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                            <b>2.3.</b>
                        
                        顺序表的操作
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                            <b>2.4.</b>
                        
                        Python中的顺序表
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                            <b>3.</b>
                        
                        链表
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                            <b>3.1.</b>
                        
                        单向链表
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                            <b>3.2.</b>
                        
                        单项循环链表
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                            <b>3.3.</b>
                        
                        双向链表
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                            <b>4.</b>
                        
                        栈
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                            <b>4.1.</b>
                        
                        栈结构实现
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                        队列
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                        队列的实现
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                        双端队列
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                        排序与搜索
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                            <b>6.1.</b>
                        
                        冒泡排序
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                            <b>6.2.</b>
                        
                        选择排序
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                            <b>6.3.</b>
                        
                        插入排序
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                            <b>6.4.</b>
                        
                        快速排序
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                            <b>6.5.</b>
                        
                        希尔排序
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                            <b>6.6.</b>
                        
                        归并排序
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                            <b>6.7.</b>
                        
                        常见排序算法效率比较
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                            <b>6.8.</b>
                        
                        搜索
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                        树与树算法
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                        二叉树
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                        二叉树的遍历
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                        <h1 id="&#x53CC;&#x5411;&#x94FE;&#x8868;">&#x53CC;&#x5411;&#x94FE;&#x8868;</h1>
<p>&#x4E00;&#x79CD;&#x66F4;&#x590D;&#x6742;&#x7684;&#x94FE;&#x8868;&#x662F;&#x201C;&#x53CC;&#x5411;&#x94FE;&#x8868;&#x201D;&#x6216;&#x201C;&#x53CC;&#x9762;&#x94FE;&#x8868;&#x201D;&#x3002;&#x6BCF;&#x4E2A;&#x8282;&#x70B9;&#x6709;&#x4E24;&#x4E2A;&#x94FE;&#x63A5;&#xFF1A;&#x4E00;&#x4E2A;&#x6307;&#x5411;&#x524D;&#x4E00;&#x4E2A;&#x8282;&#x70B9;&#xFF0C;&#x5F53;&#x6B64;&#x8282;&#x70B9;&#x4E3A;&#x7B2C;&#x4E00;&#x4E2A;&#x8282;&#x70B9;&#x65F6;&#xFF0C;&#x6307;&#x5411;&#x7A7A;&#x503C;&#xFF1B;&#x800C;&#x53E6;&#x4E00;&#x4E2A;&#x6307;&#x5411;&#x4E0B;&#x4E00;&#x4E2A;&#x8282;&#x70B9;&#xFF0C;&#x5F53;&#x6B64;&#x8282;&#x70B9;&#x4E3A;&#x6700;&#x540E;&#x4E00;&#x4E2A;&#x8282;&#x70B9;&#x65F6;&#xFF0C;&#x6307;&#x5411;&#x7A7A;&#x503C;&#x3002;</p>
<p><img src="../images/&#x53CC;&#x5411;&#x94FE;&#x8868;.png" alt="&#x53CC;&#x5411;&#x94FE;&#x8868;"></p>
<h2 id="&#x64CD;&#x4F5C;">&#x64CD;&#x4F5C;</h2>
<ul>
<li>is_empty() &#x94FE;&#x8868;&#x662F;&#x5426;&#x4E3A;&#x7A7A;  </li>
<li>length() &#x94FE;&#x8868;&#x957F;&#x5EA6;</li>
<li>travel() &#x904D;&#x5386;&#x94FE;&#x8868;</li>
<li>add(item) &#x94FE;&#x8868;&#x5934;&#x90E8;&#x6DFB;&#x52A0;  </li>
<li>append(item)  &#x94FE;&#x8868;&#x5C3E;&#x90E8;&#x6DFB;&#x52A0;  </li>
<li>insert(pos, item) &#x6307;&#x5B9A;&#x4F4D;&#x7F6E;&#x6DFB;&#x52A0;  </li>
<li>remove(item) &#x5220;&#x9664;&#x8282;&#x70B9;   </li>
<li>search(item) &#x67E5;&#x627E;&#x8282;&#x70B9;&#x662F;&#x5426;&#x5B58;&#x5728;  </li>
</ul>
<h2 id="&#x5B9E;&#x73B0;">&#x5B9E;&#x73B0;</h2>
<pre><code class="lang-python"><span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Node</span><span class="hljs-params">(object)</span>:</span>
    <span class="hljs-string">&quot;&quot;&quot;&#x53CC;&#x5411;&#x94FE;&#x8868;&#x8282;&#x70B9;&quot;&quot;&quot;</span>
    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">__init__</span><span class="hljs-params">(self, item)</span>:</span>
        self.item = item
        self.next = <span class="hljs-keyword">None</span>
        self.prev = <span class="hljs-keyword">None</span>


<span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">DLinkList</span><span class="hljs-params">(object)</span>:</span>
    <span class="hljs-string">&quot;&quot;&quot;&#x53CC;&#x5411;&#x94FE;&#x8868;&quot;&quot;&quot;</span>
    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">__init__</span><span class="hljs-params">(self)</span>:</span>
        self._head = <span class="hljs-keyword">None</span>

    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">is_empty</span><span class="hljs-params">(self)</span>:</span>
        <span class="hljs-string">&quot;&quot;&quot;&#x5224;&#x65AD;&#x94FE;&#x8868;&#x662F;&#x5426;&#x4E3A;&#x7A7A;&quot;&quot;&quot;</span>
        <span class="hljs-keyword">return</span> self._head == <span class="hljs-keyword">None</span>

    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">length</span><span class="hljs-params">(self)</span>:</span>
        <span class="hljs-string">&quot;&quot;&quot;&#x8FD4;&#x56DE;&#x94FE;&#x8868;&#x7684;&#x957F;&#x5EA6;&quot;&quot;&quot;</span>
        cur = self._head
        count = <span class="hljs-number">0</span>
        <span class="hljs-keyword">while</span> cur != <span class="hljs-keyword">None</span>:
            count += <span class="hljs-number">1</span>
            cur = cur.next
        <span class="hljs-keyword">return</span> count

    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">travel</span><span class="hljs-params">(self)</span>:</span>
        <span class="hljs-string">&quot;&quot;&quot;&#x904D;&#x5386;&#x94FE;&#x8868;&quot;&quot;&quot;</span>
        cur = self._head
        <span class="hljs-keyword">while</span> cur != <span class="hljs-keyword">None</span>:
            <span class="hljs-keyword">print</span> cur.item,
            cur = cur.next
        <span class="hljs-keyword">print</span> <span class="hljs-string">&quot;&quot;</span>

    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">add</span><span class="hljs-params">(self, item)</span>:</span>
        <span class="hljs-string">&quot;&quot;&quot;&#x5934;&#x90E8;&#x63D2;&#x5165;&#x5143;&#x7D20;&quot;&quot;&quot;</span>
        node = Node(item)
        <span class="hljs-keyword">if</span> self.is_empty():
            <span class="hljs-comment"># &#x5982;&#x679C;&#x662F;&#x7A7A;&#x94FE;&#x8868;&#xFF0C;&#x5C06;_head&#x6307;&#x5411;node</span>
            self._head = node
        <span class="hljs-keyword">else</span>:
            <span class="hljs-comment"># &#x5C06;node&#x7684;next&#x6307;&#x5411;_head&#x7684;&#x5934;&#x8282;&#x70B9;</span>
            node.next = self._head
            <span class="hljs-comment"># &#x5C06;_head&#x7684;&#x5934;&#x8282;&#x70B9;&#x7684;prev&#x6307;&#x5411;node</span>
            self._head.prev = node
            <span class="hljs-comment"># &#x5C06;_head &#x6307;&#x5411;node</span>
            self._head = node

    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">append</span><span class="hljs-params">(self, item)</span>:</span>
        <span class="hljs-string">&quot;&quot;&quot;&#x5C3E;&#x90E8;&#x63D2;&#x5165;&#x5143;&#x7D20;&quot;&quot;&quot;</span>
        node = Node(item)
        <span class="hljs-keyword">if</span> self.is_empty():
            <span class="hljs-comment"># &#x5982;&#x679C;&#x662F;&#x7A7A;&#x94FE;&#x8868;&#xFF0C;&#x5C06;_head&#x6307;&#x5411;node</span>
            self._head = node
        <span class="hljs-keyword">else</span>:
            <span class="hljs-comment"># &#x79FB;&#x52A8;&#x5230;&#x94FE;&#x8868;&#x5C3E;&#x90E8;</span>
            cur = self._head
            <span class="hljs-keyword">while</span> cur.next != <span class="hljs-keyword">None</span>:
                cur = cur.next
            <span class="hljs-comment"># &#x5C06;&#x5C3E;&#x8282;&#x70B9;cur&#x7684;next&#x6307;&#x5411;node</span>
            cur.next = node
            <span class="hljs-comment"># &#x5C06;node&#x7684;prev&#x6307;&#x5411;cur</span>
            node.prev = cur



    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">search</span><span class="hljs-params">(self, item)</span>:</span>
        <span class="hljs-string">&quot;&quot;&quot;&#x67E5;&#x627E;&#x5143;&#x7D20;&#x662F;&#x5426;&#x5B58;&#x5728;&quot;&quot;&quot;</span>
        cur = self._head
        <span class="hljs-keyword">while</span> cur != <span class="hljs-keyword">None</span>:
            <span class="hljs-keyword">if</span> cur.item == item:
                <span class="hljs-keyword">return</span> <span class="hljs-keyword">True</span>
            cur = cur.next
        <span class="hljs-keyword">return</span> <span class="hljs-keyword">False</span>
</code></pre>
<p><strong> &#x6307;&#x5B9A;&#x4F4D;&#x7F6E;&#x63D2;&#x5165;&#x8282;&#x70B9; </strong></p>
<p><img src="../images/&#x53CC;&#x5411;&#x94FE;&#x8868;&#x6307;&#x5B9A;&#x4F4D;&#x7F6E;&#x63D2;&#x5165;&#x5143;&#x7D20;.png" alt="&#x53CC;&#x5411;&#x94FE;&#x8868;&#x6307;&#x5B9A;&#x4F4D;&#x7F6E;&#x63D2;&#x5165;&#x5143;&#x7D20;"></p>
<pre><code class="lang-python">    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">insert</span><span class="hljs-params">(self, pos, item)</span>:</span>
        <span class="hljs-string">&quot;&quot;&quot;&#x5728;&#x6307;&#x5B9A;&#x4F4D;&#x7F6E;&#x6DFB;&#x52A0;&#x8282;&#x70B9;&quot;&quot;&quot;</span>
        <span class="hljs-keyword">if</span> pos &lt;= <span class="hljs-number">0</span>:
            self.add(item)
        <span class="hljs-keyword">elif</span> pos &gt; (self.length()-<span class="hljs-number">1</span>):
            self.append(item)
        <span class="hljs-keyword">else</span>:
            node = Node(item)
            cur = self._head
            count = <span class="hljs-number">0</span>
            <span class="hljs-comment"># &#x79FB;&#x52A8;&#x5230;&#x6307;&#x5B9A;&#x4F4D;&#x7F6E;&#x7684;&#x524D;&#x4E00;&#x4E2A;&#x4F4D;&#x7F6E;</span>
            <span class="hljs-keyword">while</span> count &lt; (pos-<span class="hljs-number">1</span>):
                count += <span class="hljs-number">1</span>
                cur = cur.next
            <span class="hljs-comment"># &#x5C06;node&#x7684;prev&#x6307;&#x5411;cur</span>
            node.prev = cur
            <span class="hljs-comment"># &#x5C06;node&#x7684;next&#x6307;&#x5411;cur&#x7684;&#x4E0B;&#x4E00;&#x4E2A;&#x8282;&#x70B9;</span>
            node.next = cur.next
            <span class="hljs-comment"># &#x5C06;cur&#x7684;&#x4E0B;&#x4E00;&#x4E2A;&#x8282;&#x70B9;&#x7684;prev&#x6307;&#x5411;node</span>
            cur.next.prev = node
            <span class="hljs-comment"># &#x5C06;cur&#x7684;next&#x6307;&#x5411;node</span>
            cur.next = node
</code></pre>
<p><strong> &#x5220;&#x9664;&#x5143;&#x7D20; </strong></p>
<p><img src="../images/&#x53CC;&#x5411;&#x94FE;&#x8868;&#x5220;&#x9664;&#x8282;&#x70B9;.png" alt="&#x53CC;&#x5411;&#x94FE;&#x8868;&#x5220;&#x9664;&#x8282;&#x70B9;"></p>
<pre><code class="lang-python">    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">remove</span><span class="hljs-params">(self, item)</span>:</span>
        <span class="hljs-string">&quot;&quot;&quot;&#x5220;&#x9664;&#x5143;&#x7D20;&quot;&quot;&quot;</span>
        <span class="hljs-keyword">if</span> self.is_empty():
            <span class="hljs-keyword">return</span>
        <span class="hljs-keyword">else</span>:
            cur = self._head
            <span class="hljs-keyword">if</span> cur.item == item:
                <span class="hljs-comment"># &#x5982;&#x679C;&#x9996;&#x8282;&#x70B9;&#x7684;&#x5143;&#x7D20;&#x5373;&#x662F;&#x8981;&#x5220;&#x9664;&#x7684;&#x5143;&#x7D20;</span>
                <span class="hljs-keyword">if</span> cur.next == <span class="hljs-keyword">None</span>:
                    <span class="hljs-comment"># &#x5982;&#x679C;&#x94FE;&#x8868;&#x53EA;&#x6709;&#x8FD9;&#x4E00;&#x4E2A;&#x8282;&#x70B9;</span>
                    self._head = <span class="hljs-keyword">None</span>
                <span class="hljs-keyword">else</span>:
                    <span class="hljs-comment"># &#x5C06;&#x7B2C;&#x4E8C;&#x4E2A;&#x8282;&#x70B9;&#x7684;prev&#x8BBE;&#x7F6E;&#x4E3A;None</span>
                    cur.next.prev = <span class="hljs-keyword">None</span>
                    <span class="hljs-comment"># &#x5C06;_head&#x6307;&#x5411;&#x7B2C;&#x4E8C;&#x4E2A;&#x8282;&#x70B9;</span>
                    self._head = cur.next
                <span class="hljs-keyword">return</span>
            <span class="hljs-keyword">while</span> cur != <span class="hljs-keyword">None</span>:
                <span class="hljs-keyword">if</span> cur.item == item:
                    <span class="hljs-comment"># &#x5C06;cur&#x7684;&#x524D;&#x4E00;&#x4E2A;&#x8282;&#x70B9;&#x7684;next&#x6307;&#x5411;cur&#x7684;&#x540E;&#x4E00;&#x4E2A;&#x8282;&#x70B9;</span>
                    cur.prev.next = cur.next
                    <span class="hljs-comment"># &#x5C06;cur&#x7684;&#x540E;&#x4E00;&#x4E2A;&#x8282;&#x70B9;&#x7684;prev&#x6307;&#x5411;cur&#x7684;&#x524D;&#x4E00;&#x4E2A;&#x8282;&#x70B9;</span>
                    cur.next.prev = cur.prev
                    <span class="hljs-keyword">break</span>
                cur = cur.next
</code></pre>
<p><strong> &#x6D4B;&#x8BD5; </strong></p>
<pre><code class="lang-python"><span class="hljs-keyword">if</span> __name__ == <span class="hljs-string">&quot;__main__&quot;</span>:
    ll = DLinkList()
    ll.add(<span class="hljs-number">1</span>)
    ll.add(<span class="hljs-number">2</span>)
    ll.append(<span class="hljs-number">3</span>)
    ll.insert(<span class="hljs-number">2</span>, <span class="hljs-number">4</span>)
    ll.insert(<span class="hljs-number">4</span>, <span class="hljs-number">5</span>)
    ll.insert(<span class="hljs-number">0</span>, <span class="hljs-number">6</span>)
    <span class="hljs-keyword">print</span> <span class="hljs-string">&quot;length:&quot;</span>,ll.length()
    ll.travel()
    <span class="hljs-keyword">print</span> ll.search(<span class="hljs-number">3</span>)
    <span class="hljs-keyword">print</span> ll.search(<span class="hljs-number">4</span>)
    ll.remove(<span class="hljs-number">1</span>)
    <span class="hljs-keyword">print</span> <span class="hljs-string">&quot;length:&quot;</span>,ll.length()
    ll.travel()
</code></pre>

                    
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